Reclaimed copper refining is a process comprising the following: the blister copper and the scrap copper are used as raw materials to process and refine the refined copper with the copper content≥99.3%, then casting moulding, to make the copper ingots or anode plates.
The anode furnace operations for reclaimed copper refining include four stages: feeding, oxidation, reduction and casting. The temperature of the flue gas discharged in the oxidation stage is 1200˜1300° C.; and the flue gas contains a large amount of dusts and carries semi-molten metal particles. During the reduction stage, the heavy oil is used as a reducing agent, to achieve a utilization rate less than 30%; the remaining will be discharged together with the flue gas, and the flue-gas temperature in the reduction stage is as high as 1400° C. During the reclaimed copper refining, flue gas may carry more than half of the total energy consumption of the metal smelting. Therefore, the residual heat carried by flue gas is valuable heat energy resource during the reclaimed copper refining and it is of great importance to recycle them for energy conservation. Besides, the recycling of the heat energy carried by flue gas in the reclaimed copper refining process is an important part for the enterprises to reduce energy consumption and production costs.
The large amount of flue gas and dust producing in the reclaimed copper refining process contains copper metal and other valuable elements. In order to enhance the smelting recycling rate, recycle the valuable elements and reduce environmental pollution, it is important for recycling of flue gas and dust, having important economic and environmental benefits.
In prior art, the recycling of residual heat in flue gas during reclaimed copper refining mainly adopts the residual heat boiler; and only the high-temperature residual heat is recycled, the moderate and low-temperature residual heat is not completely recycled, moreover, the heat exchange efficiency of traditional residual heat boilers is low. Therefore, the residual heat recycling rate is still low and some residual heat will be discharged to the air with the exhaust gas, which will not only waste energy sources, but also pollute the environment.
In prior art, the method for recycling dust in flue gas during reclaimed copper refining includes the dry dust recycling method and the wet dust recycling method. The dry dust recycling method is mainly used, but it has the shortcomings such as unstable process control, burning of bag collector, or blocking of bags, which may cause parking and seriously affect the sable production; besides, it has a high energy consumption and incomplete dust recycling; and it will cause environmental pollution when emissions of exhaust gas into the air.
It is expected to seek for an ideal method for recycling residual heat and dust in flue gas during reclaimed copper refining that can be used for recycling of high-temperature residual heat and moderate and low-temperature residual heat with high recycling rate, complete dust recycling and low costs.